From Reuters: The U.S. military launched a secret propaganda effort during the height of the COVID-19 pandemic to cast doubt on China's lifesaving vaccine, essentially running an anti-vax campaign in the Philippines.
Sinovac wasn't approved in the EU that alone was enough to "cast doubt" on it. Like any entity should that refuses discloses the results of clinical trials
US does this kind of stuff all the time, and if you point this out, people will call you a conspiracy theorist or bang on about how Russia is worst. The US is the world leader in this kind of thing.
I don't believe anything that the Chinese regime alleges. They are guilty as hell for COVID and for the deaths and grief they have caused worldwide. Enough is enough!